Poorly built, moisture-exposed, wood is generally exposed, to slow bacterially caused rotting and also to fungal infestation and is degraded over a relatively long time period. By lowering the moisture content to approximately 12%, and likewise by treatment with biocides, the degradation may be delayed. In the latter case, however, a rather hydrophilic material is obtained, since naturally degraded wood always resorbs a certain amount of water.
Wood which, although it is externally dry, still possesses a certain core moisture and has been sealed with surface coatings which possess only a low water vapor permeability must also be considered critically. For a lasting treatment of such surfaces, the only means that are known for preserving degraded woods are those using biocidal products or coatings which, however, generally do not meet all of the problems of wood protection and environmental protection. Generally, therefore, the efficacy of the known surface coatings is described as too low.
In addition, it is known that in the current prior art, polyolefin, PET, PA and PVC films are preferably used as coating films for consolidation and waterproofing and also covering of surfaces and as a moisture, vapor and heat barrier in construction, agriculture and forestry, but also in horticulture and landscaping. A disadvantage in this case is the high, manual effort in blanketing or covering, in particular in the case of complex surface geometries or particular structures (silo coverings, early-harvesting films, etc.).
As an alternative to this prior art, the German laid-open application DE 10 2009 049 284 describes a film that can foe applied at least in regions by spraying or coating as a functional layer of a building cladding and vapor barrier for wood structures.
There, plastics dispersions based on synthetic polymers, preferably acrylate/methacrylate, or polyurethane, are used. As a usable plastic, cellulose is also mentioned, but any teaching regarding films based on cellulose is lacking in the meaning of film sections that, can be applied at least in regions by spraying or coating, and possible embodiments thereof.
Film formation from the applied dispersion coating is based preferably on physical and mechanical adhesion of the plastics particles during evaporation of the solvent/dispersant. Therefore, the mechanical properties are limited and can only be adjusted within very narrow limits. To achieve the spraying and film properties, in addition, various additives are absolutely necessary, such as, e.g., antifoams and thickeners. A biodegradability is not adjustable. No functional activities are described, for example, against microorganisms and against feeding pests.
Patent DE 695 23 127 T2 introduces the invention of a crosslinkable cellulose additive for use in latex coating materials. Components of the additive are cellulose ethers, substituted by a hydrophilic alkene group. Crosslinking in this case is possibly only via biradical oxygen initiated by catalysts. This additive serves exclusively as thickener and agent modifying rheology; it promotes the crosslinking of latex paints.
Latex compositions comprising the additives serve for replacement of oil-based compositions and therefore the replacement of paints having a high VOC content. The content of cellulose ether additive in the latex matrix is 0.05 to 3.00% by weight. Latex polymers consist of differing, generally synthetic, macromolecules, generally based on acrylates and are commercially conventional. The crosslinkable additives are produced in the patent by reaction of monounsaturated to polyunsaturated aromatic and aliphatic glycidyl ether derivatives with cellulose ethers. The crosslinking reaction takes place here catalytically in the presence of MnSO4 or CoCl2 by addition reaction of a cyclic ether.
Patent DE 103 08 236 describes biodegradable agricultural liquid films based on polyhydroxypolyethers. These are produced with considerable complexity and use of toxic chemicals such as, for example, formic acid, hydrogen peroxide, phosphoric acid and sulfuric acid, by acid-catalytic chemical reactions at temperatures of 80-120° C., which is at the expense of the cost/benefit ratio. After atomization of the water/acetone solution or suspension, the film formation itself takes place in turn only via a pure mechanical pathway via adhesion of the soil particles. The field of application is therefore restricted to soil application, a film having inherent stability is not formed, as a result of which no further applications are possible. This is also opposed by the insufficiently controllable biodegradability. Furthermore, the application proceeds via atomization of water/acetone mixtures, which is unacceptable, for example, for use in the indoor sector.
DE 10 2005 053 587 describes the production of temporarily degradable films for agriculture, based on an alkali metal silicate solution or dispersion to which are admixed biodegradable native oligopolyols. The spraying solution is produced in a plurality of steps and is extremely complex from chemical and technological aspects (temperatures up to 200° C., use of a 50% strength potassium hydroxide solution, filtration processes). Despite the use of plasticizing components, the mechanical properties are only adjustable with restrictions. Silicates yield naturally brittle and hard moldings.
Finally, U.S. Pat. No. 2,329,741 describes the production of films from hydroxyalkylcelluloses by crosslinking reactions with bifunctional aldehydes. No cellulosic main component such as, e.g., wood pulp, recycled cellulose or sawdust, is used. Solely cellulose derivatives are crosslinked, whereby a completely different crosslinking structure results, which cannot cover a broad field of application. Furthermore, the costs with sole use of heteroglycan polysaccharide derivatives are markedly higher, in particular in the case of gellans and xanthans. The crosslinking takes place at a temperature of 105° C., which makes a practical wet processing virtually impossible.
WO 2008/112419 A2 relates to a storage-stable aqueous latex paint which contains titanium oxide, vinyl acrylic latex, acrylic latex and PVC. Cross linking via acetyl or ketal formation does not take place in this system. Spacer compounds are just as little mentioned in the abovementioned patent that are chemically incorporated into sprayed films and themselves already have biological and fire-retardant properties and moreover affect, the physical properties of the coating depending on the type of the polyol. Likewise, no chemical crosslinking would have to take place via the latex paint with the surface that is to be coated, but if it does, then it is in a considerably different manner than acetylization or ketalization.
The main components of this coating are water, polyvinyl chloride, acrylic latex, vinyl acrylic latex and TiO2, cellulose derivatives are only subordinate components.